Copolymers are an important class of polymers and have numerous commercial applications. For instance, their unique properties, whether in pure form, in blends, in melts, in solutions, in dispersions, and so forth, lead to their use in a wide range of medical products.
As a specific example, numerous copolymer-based medical articles have been developed for implantation or insertion into the body. For instance, various state of the art medical devices consist of a medical device substrate with a copolymer-containing coating that serves as a reservoir for one or more therapeutic agents. Specific examples include drug eluting coronary stents, commercially available from Boston Scientific Corp. (TAXUS), Johnson & Johnson (CYPHER) and others, which have become the standard of care for maintaining vessel patency after balloon angioplasty. These products are based on metallic expandable stents with copolymer-containing coatings that release antirestenotic drugs in a profile effective to inhibit the smooth muscle proliferation that is associated with restenosis (vessel reclosure). CYPHER stents are coated with a layer of a blend of ethylene-vinyl acetate copolymer and poly(n-butyl methacrylate) and contain sirolimus as an anti-restenotic agent. R. Virmani et al., Circulation 2004 Feb. 17, 109(6) 701-5. The polymer carrier technology in the TAXUS drug-eluting stent consists of a thermoplastic elastomer poly(styrene-b-isobutylene-b-styrene) (SIBS) with microphase-separated morphology resulting in optimal properties for a drug-delivery stent coating. S. Ranade et al., “Physical characterization of controlled release of paclitaxel from the TAXUS™ Express2™ drug-eluting stent,” Journal of Biomedical Materials Research Part A, 71A (2004) 625-634.
Another example of a medical copolymer is a synthetic phosphorylcholine copolymer, specifically, a copolymer of 2-methacryloyloxyethyl phosphorylcholine and lauryl methacrylate, which has been proposed for use in medical devices. See, e.g., A. L. Lewis et al., J. Chem. Ed., 79(3), March 2002, 321-326.
There is a continuing need for novel copolymers, which can be used in medical products, including pharmaceutical compositions and medical articles such as implantable and insertable medical devices, among others.